Method and apparatus for separating granular material



Aug. 19, 1952 J. .G. WHITFIELD Y 5 2 METHOD AND APPARATUS FOR SEPARATING GRANULAR MATERIAL Filed June 8, 1949 2- SHEETS-SHEET 1 INVENTOR. e]. '6: Whit/229M Afiozvzqys Patented Aug. 19, 1952 UNITED STATES PATENT OFFICE METHOD APPARATUS F OR SEPARAT- ING GRANULAR MATERIAL Jesse G. Whitfield, Kitts, Ky. Application June 8, 1949, Serial No. 97,773

. 8 Claims. 1

This invention relates to new and useful improvements in a method and apparatus for separating granular particles. The invention specifically relates to the art of classifying granular material such as coal and the foreign material which is normally mined therewith.

, The primary object of the invention is to provide a device that will readily and efficiently efiect separation between coal and foreign particles in accordance with the specific gravities of the different materials without the use of screens or shaking tables. In devices which use screens or shaking tables, cumbersome apparatus requiring a large amount of space is necessary. The present invention provides an apparatus which is entirely self-cleaning and in which the process is entirely continuous with the clean coal running off continuously through one chute and the foreign material running off into another or plurality of chutes in accordance with the specific gravity of the material.

Another object of the invention is to provide an improved separator in which the raw coal with the impurities is fed on to a rotating disk, the disk being submerged in water or other desired liquid medium, whereby the separation or grading of the material is accomplished by a combined action of centrifugal force and gravity separation.

Another object is to provide an apparatus of the type described inwhich the rotating disk is surrounded by concentric chambers which are normally filled with water orother suitable liquid, whereby the material thrown from the disk will sink in theliquid in the form of concentric rings to efiect the desired separation between the materials.

Another object is to provide a novel method for separating granular material in which a combination of centrifugal force and flotation of the materials being separated, is utilized.

Other and further objects will become readily apparent from the following description when considered in connection with the accompanying drawings, illustrating an embodiment of the invention, and in which:

Figure 1 is a partial vertical section showing the essential elements of separator apparatus made in accordance with the present invention;

Figure 2 is a sectional plan view on line 2-2 of Figurel; and

Figure 3 is an enlarged Figure 2.

vertical section of The illustrative embodiment of the invention shown in the drawings comprises aseparating able transverse supporting frame 2. The supporting frame 2 in turn may be supported in a building or tower. Since the complete support structure constitutes no part of the invention, it is not believed necessary to describe further details of the supporting structure.

The separating hopper I is provided with concentric bafiles 3, 4 and 5 which divide the separating hopper into a plurality of separating chambers. Suitable spiral bottoms 6 and 1 extending between the respective cylindrical bafiies constitute suitable discharge chutes, the discharge chute 6 receiving the heavier foreign particles such as the rock and shale which are separated from the raw coal, and the chute 1 receiving the clean, washed coal. The manner in which this separation is effected will be hereinafter described.

The separation hopper I is adapted to be kept full of water which is continuously circulated in through the water inlet 8 and out through the overflow pipe 9. It is to be noted that preferably the water level in the separating hopper l is to be maintained above the tops of the bafiles 3, 4 and 5 although the latter are adjustable in height in order to vary the separation action to adapt it to the material to be separated. To this end, a suitable annular angle-iron band II is suitably secured to the inner walls of the separating hopper l, the horizontal flange of the band ll constituting a supporting base for adjustable jacks I2. The screw-threaded jacks l2 are engaged by suitable brackets l4 which extend laterally from an annular supporting ring which support the baffles 3, 4 and. 5. It will be readily apparent by rotating the jacks 12 that the height of the baffles can be adjusted.

A centrifugal disk I! is mounted for rotation on the vertical axis of the separating hopper I. This centrifugal disk I! is fixed to a depending hollow shaft l8, the upper end of which is journaled in suitable bearing l9 carried by the transverse support 2. Suitable means are provided in the form of gearing 2i and suitable drive belt 22 for rotating the shaft l8. The lower end of the shaft I8 is journaled at 26 in a bearing supported in thecenter of a special throat 21 through which the 4 water in the separating hopper I is constantly recirculated by means of a suitable propeller 28.

As will be readily apparent from Figure 3,.the inner baffle 3 has suitably secured thereto as by welding, an annular flange 29 to which are welded suitable gusset plates 3|. The. gusset plates 3| in turn are welded to the throat 2'] to support the latter. The bearing 26 is supported shaft 3? can be driven through suitable means such asbelt 38 which engages the pulley 38. The propeller 28 is driven in the proper direction so that the water is circulated upwardly through a throat 2'! as shown by the arrows.

The underside of the disk I! is provided with a conical hub i'la on which are located suitable inclined ribs I'lb. In general, it is immaterial which direction the disk I! is rotated so long as the direction of rotation is properly related to the inclination of the ribs ill) to facilitate the outward and upward thrust on the water which is being forced upwar'dly'by the propeller 28 through the annular orifice 40, between the outer edge of the disk ilb 'and the upper edge of the throat 21'.

In order that the orifice e0 may be adjusted as to width, independently of vertical adjustment of the baffles, the disk H and its associated hub may be adjustable on the shaft [8. To this" end, an internally threaded washer llc may be welded to the upper side ofthe disk ll. Then by rotating the disk l? relative to the shaft [8, the vertical position of the disk IT can be varied. A suitable lock nut 20; threadedly engaging shaft I 8, can be run down tight against the washer We to lock the latter.

A suitable belt conveyor t l is provided for delivering' raw coal to an inclined chute lla which directs the coal on to the upper surface of the centrifugal plate H toward the center thereof. A second conveyor 42 is provided with a watertight casing which extends up to at least the height of the water level in the separation hopper I. The'casing for the conveyor 42 is in watertight engagement with a hopper 53 into which the coal chute I discharges, the hopper 43 being attached to the inside of the separator hopper;

I. A third conveyor M is provided with a suitable water-tight casing which is in communication with a hopper Mon theinside of the separating hopper Linto which the chute 6 discharges. The

lower end of the separating hopper I is provided J with a conical section la which terminates in a sludge sump II). A fourth screw type conveyor His provided with a suitable water-tight casing which leads from the bottom of the sump lb and discharges into the water-tight casing for the conveyor 44. It willbe readily understood that in view of the fact that it is the purpose of the separation apparatus to separate the solid majterial,; i n, all of the conveyors mentioned, there will be suli cient space between the conveyors, per se, andtheir respective casings so that the water will not be drawn up with the solid material and also thatv the casingsfor the conveyors in all insltances will be water-tight to'a point at least 'abovethe overflow pipe of the separating hopper L,

'j In the operation cf the apparatus, material suchfas raw coal with all of the usual'impurities relatively high speed. The water level in the separating hopper I will be maintained approximately to the point indicated in Figure 1 which above the surface of the centrifugalplate l 1. v At the same time that the disk I! is rotated, the

propeller 28 will be rotated to circulate water at high velocity upwardly and outwardly through the orifice which is constituted by the lower outer edge of the rotating disk I! and the upper edge of the throat '21. The rotation of the disk I! causes the raw coal to be fed into the turbulent flow of water issuing from the orifice 40. This will cause the material to be thrown radially outwardly in a trajectory which will rise slightly from the outer edge of the disk IT. The velocity imparted to the solid material together with the flotation action of the water in the separating hopper I will determine the rate at which the difierent materials gradually sink; thus the lighter materials which will include the higher grade coal, will pass over bafiles 3 and d and will be deposited in the chamber between the bafiies 4 and 5 and will be discharged through the chute 1 into the conveyor 42. The heavier materials such as rocks and shale will sink faster and will be received in the chamber between the baflies 3 and i and will be discharged by chute 6 to conveyor M. In order to accommodate the method and apparatus of the presentinvention to material being processed, the baffles 3, l and 5 may be adjusted with respect to the water level by means of jacks 12, it being understood that the drive gearing in the top of the shafts l8 and 33 may be provided with a sliding spline driving engagement to accommodate such adjustment. Also it will be understood that the speed ofrotation of the disk I! could be varied to effect optimum operating conditions.

It will be readily apparent from the foregoing that the present invention provides a novel method and apparatus for separating solid materials in accordance with their specific gravities in which the separation is effected by a combination of centrifugal force and flotation while at the same time producing a turbulent action which also facilitates the separation of the different materials. Furthermore, the invention provides a very simple and inexpensive apparatus for accomplishing this result. I

In the foregoing description it is mentioned that water is used for the floating agent. It will be readily apparent that any other liquid could be used, including a mixture of water and other materials which might be desired to give a liquid having a desired specific gravity for separating specific materials. Y

The words flotation'liquid are used herein to designate any liquid which will "give some buoyant action to the particles beingseparated or graded. Itis not necessary, for example, that the specific gravity of the flotation liquid be greater than some or all of the particles. It will readily be understood from the above description that the separation of the differentparticles having different mass characteristics will be dependent upon the combined action of centrifugal force, that is, the velocity which will be imparted'to the particle as it is thrownfrom the rotating centrifugal disk and the buoyant action of the liquid. From this it will be seen that for all particles of the same density the velocity imparted to'the particle and its resistance to movement through the flotation liquid will determine the separation chamber into'which it falls. It will be understood that as the particles are discharged below the surface of the flotation liquid, that as they lose their velocity they will sink in accordance with the relation between, their specific gravities and that of the flotation liquid. It will also be seen that the flow of water which isdirectedup- 'wardly against the bottom of the conical surface of the separating disk will tend to cause the particles to be discharged from the surface of the disk in the slightly upwardly directed trajectory which will, of course, then be curved downwardly under the action of gravity.

Although the invention has been described in considerable detail, it will be apparent to those skilled in the art that many variations are possible without departing from the inventive concept.

What is claimed is:

1. Method of separating and grading granular material comprising particles having different mass characteristics, comprising the steps of r0- tating a disk under the surface of a flotation liquid causing a turbulent radially outward flow of flotation liquid from the periphery of said disk causing an upward andoutward flow of constant force of flotation liquid away from said disk, applying the material to be treated to the upper side of said disk to .discharge said material into said turbulent flow, and collecting particles of different mass characteristics in zones concentric with said rotating disk.

2. Apparatus of the type described for separating granular material comprising a separating chamber adapted to receive a flotation liquid, means for maintaining a predetermined level of liquid in said chamber, a centrifugal separating member mounted for rotation about a vertical axis within said separating chamber, means for rotating said centrifugal separating member, a series of annular baffles arranged concentrically with the axis of said centrifugal separating member, a cylindrical member coaxial with said centrifugal separating member having its upper edge disposed with respect to the periphery of said centrifugal separating member so as to constitute an annular orifice, means for circulating the liquid in said chamber upwardlyand radially outwardly through said annular orifice to establish a current of constant force, and means for supplying granular material to the upper surface of said centrifugal separating member.

3. Method of separating and grading granular material, comprising the steps of projecting the granular material in a horizontal plane in a body of liquid into a constant current in the liquid which is moving on an arc upwardly and in the direction of travel of the granular material and which crosses the projection plane of the material at an obtuse angle with respect thereto, and collecting material of difierent characteristics in zones at different distances from the intersection of said current and said projection plane.

4. Method of separating and grading granular material, comprising the steps of projecting the granular material in a horizontal plane in all directions from a central point in a body of liquid into a current of constant force in the liquid which is moving on an arc upwardly and in the directions of travel of the granular material and which crosses the projection plane of the material at points forming a circle concentric with said central projection point and at an obtuse angle with respect to said horizontal plane, and collecting material of different characteristic in annular zones concentric with said central porjection point and at different distances therefrom.

5. Method of separatingand grading granular material as claimed in claim 4, said current of water when intersecting said horizontal plane having an upward and outward spiral movement 6. Apparatus for separating and grading granular material comprising, a tank adapted to be filled with water, a plurality of concentric collecting compartments within said tank, the upper edges of said compartments being below the surface of the water in said tank, a centrifugal separating disk of less diameter than said compartments mounted for rotation concentric with said compartments and below the surface of the Water in said tank, an annular chamber concentrio with said disk and forming with said disk an annular throat to permit the passage of water upwardly and outwardly around said disk so as to cross the projected plane of said disk at an obtuse angle to said plane, means to rotate said disk, and means to cause a circulation of constant force of said water through said annular chamber and out of said annular throat.

7. Apparatus for separating and grading granular material as claimed in claim 6, said annular chamber flaring outwardly at its top, and said disk having an inverted frusto-conical base to form with said chamber said directing throat.

8. Apparatus for separating and grading granular material as claimedin claim 6, said annular chamber flaring outwardly at its top, said disk having an inverted frusto-conical base to form with said chamber said directing throat and said frusto-conical base of said disk having spirally arranged vanes upon its side Walls to impart a spiral motion to the current of water passing between said disk and said annular chamber.

JESSE G. WHITFIELD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 896,471 Seymour Aug. 18, 1908 1,470,531 Hokanson Oct. 9, 1923 1,478,761 Rousseau Dec. 25, 1923 I 1,517,509 Hokanson Dec. 2, 1924 2,003,141 Dorfan May 28, 1935 2,362,130 Glenn Nov. 7, 1944 FQREIGN PATENTS Number Country Date 184,870 Great Britain Aug. 21, 1927 680,515 France May 1, 1930 

